We did receive a dividend, so I'm not sure where that came from then, if no blocks were solved when supposedly solo mining.
We were supposed to get dividends for 5 weeks of mining, we got dividends for 1 week of mining.
The likely scenario was that equipment was off for a month, then Garr found that out, started mining (on a mining pool), and paid dividends for 1 week only.
Other possibilities:
1. he was solo mining for one month and solved no blocks
2. he mined something (either via solo or via pooled mining) but doesn't want to share it with shareholders
3. money which he mined was stolen, but Garr doesn't want to mention that to avoid panic and accusations of bad security practices
It doesn't matter what exactly have happened, as end result is the same: shareholders lost approximately 1 month worth of dividends.